On possibility of fluorescence detection of dabsylated amino acids in liquid chromatography

Dabsyl chloride is a derivatization reagent used for UV/Vis detection of amino compounds. Since the dabsyl group does not fluoresce, it has never been monitored with a fluorescent (FL) detector. The present report shows that dabsylated amino acids exemplified by serine enantiomers produce appreciable negative peaks with an FL detector due to a strong quenching effect of the dabsyl group; thus, their fluorescent determination is possible. This finding extends a repertoire of derivatizing reagents for chromatographs without a UV/Vis detector (but with an FL one). Calibration dependencies for L- and D-Ser were similar with UV/Vis and FL detectors, although the limit of detection for the former (8 μg (L), 20 μg (D)) was lower than for the latter (48 μg (L), 42 μg (D)) due to larger noise of the FL detector.